For 50 years, we have known that muscle fibre typology is an important characteristic for sports performance.1 Nevertheless, everyone seemed to have resigned themselves to the fact that the muscle fibre typology is not measurable and applicable in the daily guidance of athletes. I challenged this status quo, by successfully optimising a non-invasive method to investigate the muscle fibre typology and I applied this technique to find several new links between the muscle fibre typology and sport performance (fatigue and recovery, talent identification and injury susceptibility).

The human skeletal muscle consists of two major cell types, slow-twitch fibres (also called type I fibres) and fast-twitch fibres (or type II fibres). These fibres have distinct characteristics, as fast-twitch fibres are able to generate a large amount of power at high shortening velocities, while slow-twitch fibres have a better energy efficiency, a higher resistance to fatigue and a more robust structural integrity.2 On average, most humans will dispose of a roughly equal number of slow-twitch and fast-twitch fibres in the vastus lateralis. However, a big heterogeneity exists meaning …